In 1979, the “New Breed” of Mustang was big news. European styling and handling characteristics had been paired with an American legend. Ford capitalized on the renewed interest in the Mustang brand by having the 1979 Mustang pace the Indianapolis 500 that year. The factory Pace Car replicas that were born from this exhibition are still among the most popular and well-known Foxes some 35 years later. An article that has just been added to our collection goes over in great detail not the production Pace Car Mustangs, but the specific parts that went into the drivetrain build-up of the Roush-prepped cars tapped for actual race duty and some of the requirements these modifications satisfied.
The cover of the October, 1979 issue of Hi-Performance Cars declares, “Build Your Own Mustang Indy Pace Car Engine,” and the article within is written with the intent of passing along the recipe for the race Pace Car’s performance to the hot-rodder at home. In fact, reading between the lines, one gets the idea that someone at Ford must have been motivated by the thought that what Roush created should not seem out of reach of the enthusiasts of the day. What would be interesting is to see whether anyone tried assembling this combination in their 79 Pace Car and if the car survived as an example of a period-correct modified car. Chances are slim that one would turn up, but stranger things have happened.
Short summary of modifications:
• Block: Stock 5.0L/302 block with custom machining by Jack Roush Performance Engineering
• Crank: 1969/early 1970 Boss 302 spec, balanced for this particular combo
• Rods: Boss 302 spec
• Pistons: TRW, milled .040, with larger valve reliefs cut
• Valve springs: 351W
• Spring retainers, rocker-arm studs & nuts: 289 Hi-Po spec
• Push rods & guide plates: unspecified aftermarket with hardening/heat treating performed by Roush Engineering
• Oil pump: unspecified high-performance oil pump and drive shaft, high flow, 80 PSI
• Oil pan: 7 quart capacity
• Camshaft: 1970 Boss 302
• Cylinder heads: “early” 351 W milled .080, 51cc chambers, yielding 10.9:1 compression
• Valves: 1.84 intake with .06 seat width and 1.54 exhaust with .08 seat width. 3-angle valve job.
• Intake: Ford dual-plane, high rise aluminum. Milled to match block.
• Carb: 600 cfm Holley R 6989 AAA 4-bbl modified by Roush
• Air cleaner: Ford Police-Interceptor, chromed
• Exhaust: “basically” factory 5.0L/2.3T performance exhaust, with converter removed
• Radiator: unspecified but larger
• Transmission: C-4 with modifications and external cooler
• Stall converter: 1978 10.25” modified for proper fit
• Rear gear ratio: 3.08:1
• Brakes: Fairmont Police Package semi-metallic pads
• Suspension: largely the stock TRX set-up with stiffer-valved stock shocks and lighter load springs (same spring rate) which lowered the car 1”/.5” front/rear.
• Tires: Goodyear Wingfoot Radials due to sponsorship considerations
Further detail and specs can be found, along with part numbers (!) by reading the entire scanned article available here
. The intake manifold was not available for purchase, so the author gives a suggestion on an appropriate substitution. And, if you have tried or decide to try this yourself, let us know!